1. Field of the Invention
The present invention relates to a cleaning device for use with the electrophotographic copying machine and the like.
2. Prior Art
As the cleaning device for use with the electrophotographic copying machine and the like, there have been well known in the art those of the magnetic brush type, of the blade type, of the fur brush type and of the other types.
The one of the magnetic brush type is intended to absorb and eliminate residual particles of toner from the surface of a photosenstive body in such a way that a non-magnetic cylindrical sleeve in which plural magnets are arranged different in polarity from one another, is located adjacent to the surface of the photosensitive body, that fine magnetic particles are absorbed on the sleeve to form a magnetic brush, and that the magnetic brush is contactedly rotated an slid relative to the surface of the photosensitive body.
The one of the blade type is intended to eliminate the remaining particles of toner by pressing a blade, made of a resilient material, against the surface of the photosensitive body.
The one of the fur brush type is intended to eliminate the residual particles of toner by contactedly rotating and sliding a fur brush relative to the surface of the photosensitive body.
The magnetic brush type has a certain degree of cleaning capacity but it is insufficient for cleaning those particles of toner which are not transferred but left on the whole surface of the photosensitive body as a uniform black toner.
The blade type cannot achieve sufficient cleaning particularly in the case of the high speed copying machine and it is likely to damage the surface of the photosensitive body because its blade is constantly pressed against the surface of the photosensitive body.
Although the fur brush type can be used for the high speed copying machine, electric charge is introduced from a retrieval roll to the fur brush because bias voltages applied to the retrieval roll which serves to collect toner from the insulating fur brush are different from one another, and the potential difference between the retrieval roll and the surface of the fur brush is thus made negligible. As a result, the toner is not retrieved from the fur brush to the retrieval roll and the fur brush is jammed by the toner, thereby making the cleaning operation impossible. Further, the manner of making the fur brush of a conductive material, applying a bias voltage to it, and applying a higher bias voltage to the insulating retrieval roll has been proposed, but the same phenomenon as mentioned above is caused, making the cleaning operation insufficient.
For the purpose of enabling the fur brush type to have a stable cleaning capacity, it is needed that the resistance value of the fur brush itself is controlled to be within a specific range, that this resistance value is kept stable under any circumstances, and that the fur brush is made of a material which makes it hard to be physically deformed and which has a strong restoring force even if it is deformed. However, those conventional materials of which the brush was made could not meet all of these needs and accordingly, stable cleaning capacity could not be achieved.